Circuit breaker



May 5, 1942. L. M. BROWN CIRCUIT BREAKER Filed July 26, 1940 3Sheets-Sheet 2 INVENTOR LOL/Z5 MBTOZUH.

Air N Y WITNESSES:

:2J HV1/6 L. M. BROWNl May 5, 194".

. CIRCUIT BREAKER Filed July 26, 1940y latentcd May/5, 1942 cmourr nimma,Louis M. Brown, wennen, N. 1.1,nhignor to Westinghouse ElectricManufacturing pany, East Pittsburgh, Pa.,

P'ennsyl Uoma corporation o Application July 26, 1940, Serial No.347,637

11 (Cl. 23h-11B) The invention relates to circuit interrupters of theenclosed type, and more particularly' to enclosed circuit breakers whichare totally immersed in a body of oil within an enclosing housing ortank.v c

Circuit breakers for use in hazardous locations where gasoline, naptha,lacquersolvent vapors, and 'other explosive materials are present, andalso where corrosive gases are encountered are usually mounted in anenclosing housing or tank and totally immersed in a body of oil withinthe housing for' complete protection against the above-mentionedconditions. The total immersion of the circuit breaker in oil hasheretofore prevented the use of conventional thermally responsiveoverload trip devices for such breakers because directconta'ct of theheater element of the thermalA unit with the oil destroys the thermalcharacteristic of the trip device. Moreover, providing a liquid tightcasing for the breaker or its trip device is not practical from eitheran 'economical or operational standpoint.

An object of vthe-present invention is the'provision of a circuitbreaker totally immersed in a body of oil within an enclosing housingand embodying athermally responsive overload trip device, the thermalvcl'ntracteristic of which is unaffected by the oil.

Another object of the invention is the provision of an explosionresisting or corrosion resisting circuit breaker apparatus comprising acircuit breaker having a magnetically responsive and a thermallyresponsive overload vtrip rdevice totally immersed in a body of oilwithin an enclosing housing with means for preventing the thermallyresponsive unit and its heater from being. in contact withthe oil.

Another object of the invention is the provision of an improvedexplosion resisting or corrosion resisting circuit interrupter aspreviously described which is simple, accurate and reliable inoperation, and inexpensive to manufacture. y 2

The novel features that are considered characteristic of the inventionare set forth in particular in the appended claims. The inventionitself, however, both as to structure and operation together withadditional objects and advantages thereof will be best understood fromthe following detailed description of one embodiment therof when read inconjunction with the accompanying drawings, in which:

Figure 1 is a vertical sectional view of the circuit breaker housingwith the circuit breaker mounted therein, I

' Fig. 2 is another vertical sectional view of the apparatus taken atright angles to the section of Fig. l,

Fig. 3 is a fragmentary sectional view on an enlarged scale showing aportion of the circuit 00. end of the tank II support spaced verticalsupporting bars 39.

breaker and tank, a part of broken away to reduce the width of thefigure, Fig. 4 is a perspective view on an enlarged scale of the tripdevice of the circuit breaker, and

- Fig. 5 is an enlarged fragmentary sectional view showing the thermallyresponsive trip means and a portion of the electromagnetic trip means ofone poleof the circuit breaker.

Referring to the drawings, the reference numeral-v l designates anexplosion resisting and corrosionresisting circuit breaker housing whichcomprises an oil tight metal tank II and a cast metal top or cover4section I3 Ywhich serves to the tank II and close the open end thereof.the cover section I3 by a plurality of captive bolts I5 and cooperatingnuts I1, the bolts I5 being carried by brackets i9 secured to the tank II in spaced relation around the upper end thereof. The bolts I5 areadapted to extend through openings provided therefor in the lugs 2|which are formed integral with the cover section I3 along the bottomedge, and the nutsv I1 are threaded on the upper ends of the bolts I5 totightly secure the tank to the cover section I3. A gasket 23 is securedto the abutting edge of the cover section I3 to provide a tight seal atthe joint between the tank and the cover section.

The rear wall of the cast metal c over section I3 is formed to provide aflat mounting base 2S which projects laterally beyond the sides of thehousing, and the base is provided with a plurality of holes 21 forreceiving bolts or cap screws to mount the housing on a suitable support. The top and side walls of the cover section I3 are provided withtapped holes' 29 for accommodating the incoming and outgoing electricalconductors which lead to the circuit breaker within the housing, itbeing understood that the electrical conductors are brought into thehousing through conduits (not shown), the ends of which aresecured inthe threaded openings 29.

A multipole circuit breaker indicated generally at 3| is disposed in a'vertical position within the lower portion of the housing andfissupported from the cover section I3. The' circuit breaker is secured bymounting bolts 33 (Figs. 2 and 3). to a verticalmounting plate 35 whichis in turn secured by brackets 31 to a pair of The supporting bars 39are carried by the cover section fl, each bar being rigidly secured atits upper end to the cover section I3 by means of a pair of cap screws4I. Y

The incoming electrical conductors 43 -and the outgoing electricalconductors 45 are held clamped in proper position adjacent the upper bya pair of transversely exthetonkbemg The tank I I is removably securedto tending clamping bars Il of insulating material which are secured attheir ends bybolts 48 to a pairgof brackets 5| carried by the supportingbars 39. The conductors 43 and 45 are also held clamped at a positionin` back of the circuit breaker 3| by apair of insulating clampingplates 53 which are secured at their ends to brackets 55 carried bythesupportin'g bars 39. The conductors 43 are electrically connected tothe three lower terminal studs 51 of the circuit breaker 3|, and theconductors. are electrically connected to three spaced terminalsy 59carried by the mounting plate 35 below the center of the breaker.' Thethree terminals 59 are in t'i'-*ielectrically connected to the upperterminal 'studs 'BI of the circuit breaker by means of conducting straps83.

The circuit breaker in the embodiment of the invention shown isv of thesame general construc tion as the circuit breaker fully described' inPatent 2,047,739 of-Harry J. Lingai, issued July 14,

1936, and assigned to the assignee of the present invention.

Referring to Fig. 3, the circuit breaker, briefly, comprises a two partcasing 65-'of molded insulating material having therein a stationarycontact 61 and a cooperating movable contact 69 for each of the threepoles. The movable contacts 69 are carried by switch arms 1| which aremechanically connected for simultaneous movement together about a commonpivot 13 by means of an insulating tie bar 15. 'I'he switch arms areactuated by one overcenter spring mechanism at the center pole ot thebreaker comprising a pair of toggle links 11 .and.19 connected to thecenter pole switch arm 1| and to a pivoted vreleasable carrier 8| whichisl pivoted at 83 on a frame 85 secured to the base of the circuitbreaker. A pivoted actuating member 81 is connected by overcentersprings 89 to the knee of the toggle for manually `actuating thecirc'uit breaker.

The trip device 9| of the circuit breaker is mounted inthe upper end ofthe circuit breaker casing 65 and normally servesy to restrain thepivoted `carrier lever 8| in the latched position shown in Fig. 3. Thetrip device is operable inl response to an overload on any of the threecircuits controlled by the circuit breaker to effect release of thecarrier 8| and thus cause automatic opening of all of the contacts ofthe breaker. When the breaker is tripped, the actuating member 81 isautomatically moved to a tripped indicating position intermediate itson" and oif positions. The circuit breaker mechanism is manually resetfollowing tripping by movement of the actuating member 81 to its ofi'position to reset the carrier lever 8| to its latched position in whichit is normallyA held by the trip device 9|.

The trip device 9| is a unitary structure entirely assembled upon itsown insulating base 93 and is completely removable from the circuit vbreaker casing 65, the screws 95 and bolts 6| being utilized to mountthe trip device in the circuit breaker casing and also to make `thenecessary electrical connections. The trip device includes a thermallyresponsive trip e1e' ment 91 and a magnetically responsive trip meansfor each of the three poles of the breaker.

The three conducting bars or strips 99, one of which is associated witheach of the polesof the breaker have the quadruple function of providingterminals for the trip device, of providing energizing means for each ofthe electromagnetic trip means, of providing heater means for -thethermally responsive elements 91, and for providing a mounting means forthe entire trip structure.

Each thermally responsive trip element 91 is composed of a strip ofbimetallic material and is fastened by 'rivets to one of the conductingstrips 99.

As shown particularly in Fig. 5, the conducting strips 99 are bent` soas to form two reflex bends |0| and |03. The straight part |05 of thestrip 99 is utilizedv as a single turn conductor for energizing themagnetically responsive trip means, while the loop |0| is utilized as aheater for the thermally responsive trip element 91. The portion of theconducting strip 99 which is used in forming the loop 0| is tapered soas to give a conducting section of gradually increased electricalresistance, thereby forming a heater for the bimetal trip element 91.The straight portion |05 of the strip 99 is not of reduced section anddoes not heat appreciably while carrying the rated current of` thebreaker. Each of the conducting strips 99 is fastened by rivets to a`:frame or bracket |01 which is, in turn, secured to the trip base 93.

The magnetically responsive trip means of each pole comprises a U-shapedcore |09 (Fig.- 4) of magnetic material secured to the bracket |01, anda movable armature which is movably vmounted for movement toward andaway from the core |09 by means of a guide pin I|3 secured to thearmature ||I and slidably mounted in an opening provided therefor in abracket |,|5 secured to the frame |01. The armature is biased ytounattracted position away from the core |091'by means of a spring ||1interposed between the bracket I5 and a collar on the guide pinl I I3,as shown in Fig. 5. The straight portion |05 of the conducting strip 99passes through the U ofthe stationary core |09 and thus forms asingleturn energizing winding for the electromagnetic trip means.

The. trip device includes a pivoted latch ||9 which is pivoted at |2|(Fig. 3) on -a bracket |23 carried on the lower side of the trip base93, and this latch is biased to latching position in which it engagesand restrains the releasable carrier 8| in latching position, as shownin Fig. 3. The latch ||9 has an upwardly extending portion whichprojects through an opening in the trip base 93 and which is adapted tobe normally engaged and held by a latch projection |25 carried by acommonV trip bar |21 to thereby hold the latch ||9 in latching position.Q

The common trip bar |21 is of molded insulat- -ing material and isadapted to be actuated to eiect release of the latch H9, and therebyrelease of the carrier 8|, by any one of the individual trip devices.This trip bar |21 has two downwardly extending arms |29, one at eachend, for engaging pivot pins `|3| which project through suitableopenings in supporting brackets |33 mounted on the trip base 93 at eachend. A second projection |35 of the trip bar extends downwardlytherefrom and through the agency of a suitable recess engages acompression spring |31 (Fig. 3) which biases the tripbar |21 to latchingposition.

The heads of the armature guide pins 3 engage in notches providedtherefor in the molded trip bar |21, thereby connecting the trip bar toeach of the movable armatures for actuation thereby. Three adjustingscrews |39I lthrough the corresponding pole.

each in a position to be engaged by the free end of one of the thermallyresponsive bimetal trip elements 91, thereby providing for actuation ofthe trip bar |21 by deflection of any one of the thermally responsivebimetal trip elements 91 when, the element is heated a predeterminedamount by overload current. -A cover |4| of molded insulating materialis secured to the upper end of the brackets |33 by fastening screws andthis cover cooperates with the ,base 93 to form an enclosure for thetrip device.

Each of the conductor strips 99 is connected at its upper-end to one ofthe upper terminals 6| of the circuit breaker, and is electricallyconnected at its lower end through the agency of a flexible shuntconductor |42 to the movable contact 69 of its corresponding pole. Thuseach l electromagnetic trip means is energized by the vcurrent flowingthrough its correspondingpole and each thermally responsive trip element91 is heated in response to the current The automatic operation of thecircuit breaker is briefly as follows. When an overload current of morethan a predetermined magnitude, for example, more than l times ratedcurrent, oc-

- curs in the circuit of any pole of the breaker, the

corresponding electromagnetic trip means is energized thereby asufficient amount to pull its movable armature to attracted position andtherebymove the trip bar |21 to effect release of the latch ||9 and thereleasable carrier 8| of the circuit breaker. The release of the carrier8| effects automatic opening of the circuit breaker,-

since the overcenter springs 89 immediately act to rotate the threeswitch arms 1| to open circuit position, and also effect collapse of thetoggle 11 and 19.

When an overload of less than the predetermined magnitude occurs in thecircuit of any pole of the breaker, the bimetallic trip element 91 'ofthat pole is heated by the overload current and if the overload persistsfor a sufficient length of time to heat the bimetallic trip element apredetermined amount, the trip element deflects upwardly away from thecircuit breaker mechanism to engage and move the trip bar |21, therebyeffecting release of the circuit breaker mechanism and automatic openingof the circuit breaker in the manner previously described.

An operating means is provided for manually operating the circuitbreaker 3| from outside of the housing 9. The operating means comprisesan operating shaft |43 which projects through a side of the coversection |3-and is rotatably mounted on the cover section in a bearing|45 provided therefor. An operating handle |41 is rigidly secured to4the portion of the operating shaft |43 which projects outside of thehousing. The operating shaft |43 is provided with a crank arm |49 on theend of the Y shaft which projects inside of the housing 9, and thiscrank arm is mechanically connected by a link |5| to a transverselyextending operating yoke |53 which is pivotally mounted at |55 on thevertical supporting bars 39. The operating yoke |53 straddles thecircuit breaker 3| and is provided with a slot |56 which engages thebreaker actuating member 81. The connecting link |5| is pivot-allyconnected at |51 to the free end of the crank arm |49 and its other endis pivotally connected at |59 to one side of the yoke |53.

The operating shaft |43 has a close flt in the opening of its bearing'|45 and the length of the flowing engaged parts of the shaft, andbearing is sufficient to make the shaft opening flame proof or flametight.

`A body of oil |6| is disposed within the tank to a level above thecircuit breaker 3| so that the circuit breaker is completely immersed inthe oil and the parts thereof are thereby protected from corrosion. Thebody of oil also prevents the arcs drawn between the contacts of thebreaker upon interruption of the circuit from igniting any explosivegases or materials which may be present in the atmosphere surroundingthe apparatus.

In order to prevent the oil within the housing from affecting thethermal characteristic of the thermally responsive means of the tripdevice, a diving bell |63 is provided which is mounted over the upperend of the circuit breaker 3|, as shown in Figs. l and 2. The divingbell |63 comprises,

carried by the vertical supporting bars 39. The f lower edge of thevessel |63 is disposed some distance below the trip device 9| of the.circuit breaker 3|, so that the vessel prevents the oil from rising uparound the trip device, lby reason of the air which is trapped withinthe upper portion of the vessel |63, as indicated in Fig. 2. I t willthus be seen that the vessel |63 prevents the oil from coming in contactwith the thermally responsive trip elements 91 and the heaters Ill'l ofthe trip device, thereby preventing the oil from affecting or destroyingthe thermal operating characteristic of the trip device. Since the tripdevice is disposed below the level of the oil, the parts thereof are notsubjected to the corrosive action of the atmosphere surrounding theapparatus.

While the invention has been disclosed in accordance with the provisionsof the patent statutes, it is to be understood that various changes inthe structural details and form of elements may be made withoutdepartingfrom the essential features of the invention. It is desired,therefore, that the appended claims be given the broadest reasonableconstruction vthat is permissible in view of the prior art and thelanguage of the claims.

I claim as my invention:

l. In combination, a circuit interrupter having relatively movablecontacts and thermally4 responsive means hea-ted in response tothecurrent of the circuit and operable when heated a predeterminedamount to cause opening of the contacts, an enclosing housing in whichthe cirsuit interrupter is mounted, said housing containing a body ofinsulating liquid in which the circuit interrupter with its thermallyresponsive means is totally immersed, and means for preventing theliquid from affecting the thermaloperating characteristics of saidthermally responsive means.

2. In combination, a circuit breaker having relatively movable contactsand thermally responsive means heated in response to the current cf thecircuit for causing automatic opening of the contacts when said means isheated a predetermined amount, an enclosing housing in which the circuitbreaker is mounted, said housing containing a body of insulating liquidin which the circuit breaker with its thermally responsive means iscompletely submerged, and

means i'or preventing the liquid from coming in contact with saidthermally responsive means.

3. In combination, a circuit breaker having K relatively movablecontacts andk thermally responsive means heated in response to thecurrent of the circuit which is operable when heated a predeterminedamount to cause opening of saidcontacts, an enclosing housing in whichthe circuit breaker is mounted containing the body of insulating liquidin which the circuit breaker with its thermally responsive means is atleast partially submerged, and a vessel closed at the top and sides andopen at the bottom surrounding said thermally responsive means toprevent the liquid from coming in contact with the thermally responsivemeans.

4. In Icombination, a circuit breaker having relatively mov-ablecontacts and a trip unit including a thermally responsive trip elementand a heating element therefor heated by -the current of the circuit,said thermal trip element being operable when heated a predeterminedamount to cause automatic opening of said contacts; an enclosing housingin which the circuit breaker is mounted, said housing containing a bodyof insulating liquid in which the circuit breaker is at least partlysubmerged, and a vessel closed at the top and sides and open at thebottom surrounding said trip unit to prevent the liquid 'from coming incontact with said thermally responsive trip element and said heaterelement.

5. In combination, a multipole circuit breaker having a plurality ofpairs of relatively movable contacts, actuating mechanism for saidcontacts, and a trip device mounted adjacent the upper end of thebreaker having a plurality of thermally responsive trip means one foreach of at least two of the poles of the breaker, each trip means beingheated in response to the current owing through its corresponding poleand each being operable when heated a predetermined amount to causeautomatic opening of the contacts of the breaker, an enclosing housingin which the circuit breaker is mounted, said housing containing a bodyof insulating liquid in which the circuit breaker with its trip deviceis at least partly submergedfand a vessel closed at its top and sidesand .Open at its bottom sur- A rounding the upper end of said breakerand the trip device to prevent the liquid 'from coming in contact withsaid thermally responsive itrip means.

6. In combination, a circuit breaker having relatively movable contacts,operating means therefor, and a trip device operable in response topredetermined current conditions to cause automatic opening of saidcontacts, an enclosing housing in which the circuit breaker is mounted,said housing containing a body of insulating liquid in which the circuitbreaker with its trip device is at least partly submerged, and a vesselclosed at the top and sides and open at the bottom surrounding said tripdevice, the bottom edge of said vessel extending into said liquid belowthe surface of the Yliqui '7. In combination, a circuit breaker havingrelatively movable contacts, operating means therefor, and a trip deviceadjacent the upper end of the breaker operable in responsie topredetermined overload conditions to cause automatic opening of thecontacts, said trip device including electromagnetictrip means energizedby the current of the circuit operable to cause the current exceeds apredetermined magnitude, and thermally responsive trip means heated inresponse to the current 4of the circuit and operinstantaneous 'trippingof the breaker Whenever 75 able to cause tripping of the breaker whensaid thermally responsive means is heated a predetermined amount byoverload current, an enclosing housing in which the circuit breaker ismounted, said housing containing a body of insulating liquid in whichsaid breaker and its trip device are at least partly submerged, and aliquid tight hood open at the bottom disposed over the trip device forpreventing the liquid from rising in contact with the heating portionsofthe trip device.

8. In combination, a housing comprising a top section and a tankremovably secured to said top section, a circuit breaker mounted in saidhousing and supported from said topl section of the housing, saidcircuit breaker having a trip device adjacent the upper end thereofincluding a thermally responsive trip means heated in response to thecurrent of the circuit and operable when heated a predetermined amountto cause opening of the breaker, said tank containing a body ofinsulating liquid in which the circuit breaker with its trip device iscompletely immersed, and a liquid tight open bottomed vessel supportedfrom said top section and surrounding the upper end of the breaker wherethe' trip device is located for preventing the liquid from coming incontact with the trip device and its thermally responsive trip means.

9. In combination, a circuit breaker havingy relatively movablecontacts, and thermally responsive means heated in response to thecurrent of the circuit which is operable when heated a predeterminedamount to cause opening of said contacts, an enclosing housing in whichthe circuit breaker is mounted containing 'a body of insulating liquidin which the circuit breaker is at least partially submerged, and a,vessel completely closed at its top and sides and open at the bottomsurrounding said thermally responsive means, the open 'bottom of saidvessel extending into said liquid below the surface thereof.

10. In combination, a circuit interrupting device having means operablein response to predeterminedabnormal conditions of the circuit to causesaid device to interrupt the circuit, an`

ing a thermally responsive means heated'in response to the currentoflthe circuit and operable when heated a predetermined amount to .causesaid interrupter to interrupt the circuit,

an enclosing housing in which said circuit interrupter is mounted, saidhousing containing a body of insulating liquid in which said circuitinterrupterV and its thermally responsive means is submerged, and' avessel closed at its top and sides and open at the bottom surroundingsaid thermally responsive means to prevent Vsaid liquid from coming incontact with said thermally responslve means.

LOUIS M. BROWN.

